Low-voltage “air” power circuit breakers were designed in the late 1930’s. For the past seventy-five years, and even today, they have been used in virtually every industrial application. Between the 1930’s and 1960’s, these breakers utilized series overload devices to sense current and provide time delays. While the series overload is a robust and reliable design, it has several limitations. Specifically, overloads do not offer the precision and selectivity available with modern electronics, and certain protective functions, such as ground fault, are simply not available.
Despite these limitations, some new breaker designs used overloads into the 1980’s. Around this time, numerous failures began to manifest due to the fact that many of the existing overloads were reaching the end of their useful life. Some of the biggest problems involved oil leaking from dashpots, and oil changing viscosity, affecting the time delay feature of the dashpots.
Because the old power breakers were well made and expected to have a long service life, they were frequently employed in critical applications that require continuous operation. Replacing a failed overload or older generation solid-state trip is often problematic because most OEMs no longer provide support for these systems. Commonly, OEMs recommend replacing the old breakers with the current production model. Not only is this approach expensive, it often requires significant downtime as switchgear needs to be replaced along with the breakers.
To address these issues, ETC released the first version of the etc upgrade system in 1988. Using this system, any vintage of US manufactured breaker from pre-WWII to present, can quickly and economically be upgraded. A properly remanufactured breaker is mechanically superior to those currently in production. The ETC-12 allows these old breakers to be updated with advanced electronic controls and ensure that they will continue to function reliably for decades.
Although most power circuit breakers that are presently in use already have been retrofitted with older generation solid state trip units, many users are choosing to upgrade these breakers with the state of the art ETC-12. This is because the ETC-12 provides more accurate metering and advanced selectivity, as well as, many features that are unavailable on lesser units. Most importantly, upgrading with the ETC-12 significantly improves operator safety with features such as the remote mountable display, flashSAFE arc-flash reducing maintenance mode , and mechanical automatic reset actuators .